The use of ultrasonic transducers to measure fluid flow is well-known. One such flow meter is disclosed in U.S. Pat. No. 5,594,181 entitled “Ultrasonic Flow Meter” and issuing to Stange on Jan. 14, 1997. Therein disclosed is an ultrasonic flow meter having two ring-shaped piezoelectric transducers with one operating as an ultrasonic transmitter and the other one as an ultrasonic receiver. The two ring-shaped piezoelectric transducers are embedded into the wall of a pipe.
Another ultrasonic flow meter is disclosed in U.S. Pat. No. 5,974,897 entitled “Ultrasonic Flow Meter” and issuing to Koyano et al on Nov. 2, 1999. Therein disclosed is an ultrasonic flow meter having three ring-shaped oscillators disposed longitudinally along a tube so as to intimately contact the inner peripheral surface of the ring-shaped oscillators with the outer peripheral surface of the tube. The center oscillator generates an ultrasonic wave that is detected by the forward and rearward oscillators to obtain the flow rate of a fluid flowing through the tube.
Yet another flow meter is disclosed in U.S. Pat. No. 6,055,868 entitled “Ultrasonic Flow Meter” and issuing to Koyano et al on May 2, 2000. Therein disclosed is an ultrasonic flow meter with two ring-shaped oscillators disposed longitudinally along the tube.
While these ultrasonic flow meters have adequately measured fluid flow they have been difficult to use in many applications, particularly where different sizes of tubes are used and where there is a need to frequently replace tubes. Accordingly, efforts have been made to accommodate different sizes of tubes or to facilitate the replacement of tubes in an ultrasonic flow meter. One such system is disclosed in U.S. Pat. No. 5,179,862 entitled “Snap-On Flow Measurement System” and issuing to Lynnworth on Jan. 19, 1993. Therein disclosed is a block having a channel therein and a retaining pin. Also disclosed therein is a semi-rigid body having a keyhole slot. The block or body is used to hold a conduit adjacent a transducer block. Another device for accommodating a conduit is disclosed in U.S. Pat. No. 7,469,598 entitled “Method of Employing a Transit Time Ultrasound Sensor” issuing to Shkarlet et al on Dec. 30, 2008. Therein disclosed is a measuring channel having an acoustic couplant contained therein for retaining a conduit in the measuring channel.
While these devices have adequately held a tube or a conduit or permitted their replacement, they have often encountered problems of coupling the ultrasonic transducer to the tube and fluid flow therein to obtain strong signals utilized for measuring the fluid flow. Therefore there is a need for an ultrasonic flow meter system that can accommodate tubing easily and yet permit the easy replacement of the tubing and in particular tubing that may be flexible and disposable tubing such as that used in medical applications in which the tubing is disposed of after each use.